This invention relates to an electrical switch operated by the input member of a hydraulic master cylinder assembly, such as the master cylinder of a motor vehicle clutch hydraulic control system or the master cylinder of a motor vehicle hydraulic brake system.
It has become general practice in the automobile industry to interlock the operation of the engine starter motor with other controls of the motor vehicle such that the starter member is rendered inoperative unless the transmission is in neutral or park in motor vehicles provided with an automatic transmission or, in motor vehicles provided with a foot operated clutch and a manually operated gear shift transmission, unless the transmission is in neutral and/or the clutch pedal is fully depressed, to fully release the clutch. In addition, it is convenient in a motor vehicle provided with a cruise control and a mechanical clutch to shut off the operation of the cruise control upon, for example, downshifting which in turn requires release of the clutch. However, it is necessary that the cruise control be disconnected even before the clutch is fully released to enable the driver to cut ore the cruise control by a slight foot tap on the clutch pedal. It is also desirable to actuate the electronic fuel control (EFI) of the motor vehicle in response to the initial depressing movement of the clutch.
Many switch arrangements have been provided for use in association with the master cylinder assembly to accomplish the various desired switching operations as the clutch pedal is depressed. Examples of such switches are shown, for example, in U.S. Pat. Nos. 4,878,041, 4,719,444, 474219 and 4,649,238. The switch devices shown in these prior art patents are all of the type in which the switch mounts on the push rod of the master cylinder assembly and in which the switch includes a plurality of axially spaced switches which can be sequentially actuated in response to depression of the clutch to generate a sequential series of control signals with respect to cruise control, EFI interlock, etc. Whereas these prior art switches have proven to be generally satisfactory, generating the required control signals in response to depression of the clutch, the sequential arrangement of the various switches along the length of the switch results in a relatively long switch assembly which is incompatible with the relatively short push rods that are found in many present day motor vehicles.